As is generally known in the art, electric vehicles (EV) are driven by battery power, resulting in reduced pollution sources such as exhaust gas and noise as compared to conventional gasoline engine vehicles. EVs are typically classified into hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EVs), depending on their driving sources. The HEV is equipped with an engine as a main power source and an electric motor as an auxiliary power source. The PHEV is equipped with an electric motor as a main power source and utilizes an engine when a battery is discharged. The EV is equipped with an electric motor as a main power source, and does not have an engine.
Wireless charging of a battery which drives the electric motor of the EV can be performed by coupling a primary coil of a charging station and a secondary coil of the EV to achieve magnetic resonance. In a magnetic resonance WPT system, if the primary and secondary coils are not properly aligned, the efficiency of the WPT may be greatly reduced. Therefore, proper alignment of the primary and secondary coils may be required.
According to a conventional alignment method, the secondary coil, which is installed in the EV, may be aligned with the primary coil using a rear camera. The primary coil may be installed in a ground assembly (GA) in a parking space. According to another conventional alignment method, once the EV is parked in a parking space, a moveable charging pad is moved so that the primary coil and the secondary coil of the EV become aligned.
However, these conventional techniques may require user interventions, thus generating user inconveniences and possible errors in the alignment of the coils, which may cause excessive system performance degradation. Therefore, in a magnetic resonance WPT system which is sensitive to the misalignment of the coils, it is difficult to achieve the optimal WPT efficiency, and the stability and reliability of the system can be reduced as a result. Accordingly, there is a need for a method of precisely aligning the primary coil of the GA in a charging station and the secondary coil of the EV to charge a high-voltage battery mounted on the EV in a WPT system.